Driving axle My design for the driving axle uses 1.75" diameter steel, and has seats for wheels, bearings,
and flycranks. My design differs from the original in that it used a single bar slidebar, which is simpler than a twin bar to align.
However, that needs move width to make it work, so the coupling rod was bent inwards towards the front to fit it all in. I shall be using
a twin bar slidebar, which allows the cylinders to be tucked slightly closer in, and uses a simple straight coupling rod. When making
the axles, the important measurement is the back to back. Use this as your datum and measure outwards from there. Remember to machine
the wheel, bearing, and flycrank seats at the same setting to ensure they are concentric.
Pony axle (outside frames)